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E I 28: 56LA-R /10MS"- 7*? /4 



SOLAR/1045-79/14 




Solar Energy System 
Performance 



MOIMTECITO PINES 

APARTMENT COMPLEX 

Santa Rosa, California 

November 1978 Through March 1979 



/ /ft,/ 



U.S. Department of Energy 

National Solar Heating and 
Cooling Demonstration Program 

National Solar Data Program 




NOTICE 

This report was prepared as an account of work sponsored by the United States 
Government. Neither the United States nor the United States Department of Energy, nor 
any of their employees, nor any of their contractors, subcontractors, or their employees, 
makes any warranty, express or implied, or assumes any legal liability or responsibility for 
the accuracy, completeness or usefulness of any information, apparatus, product or process 
disclosed, or represents that its use would not infringe privately owned rights. 



This report has been reproduced directly from the best available copy. 



Available from the National Technical Information Service, U. S. Department of 
Commerce, Springfield, Virginia 22161. 



Price: Paper Copy $5.25 
Microfiche $3.00 



SOLAR/ 1045- 79/ 14 

Distribution Category UC-59 



SOLAR ENERGY SYSTEM PERFORMANCE EVALUATION 



MONTECITO PINES 
SANTA ROSA, CALIFORNIA 



NOVEMBER 1978 THROUGH MARCH 1979 



JAMES E. HUGHES, PRINCIPAL AUTHOR 
JERRY T. SMOK, MANAGER OF RESIDENTIAL SOLAR ANALYSIS 
LARRY J. MURPHY, IBM PROGRAM MANAGER 



IBM CORPORATION 
18100 FREDERICK PIKE 
GAITHERSBURG, MARYLAND 20760 



PREPARED FOR 
THE DEPARTMENT OF ENERGY 
OFFICE OF ASSISTANT SECRETARY FOR 
CONSERVATION AND SOLAR APPLICATION 

UNDER CONTRACT EG-77-C-01-4049 
H. JACKSON HALE, PROGRAM MANAGER 



TABLE OF CONTENTS 

Page 

1 . FOREWORD 1-1 

2. SUMMARY AND CONCLUSIONS 2-1 

2.1 Performance Summary 2-1 

2.2 Conclusions 2-1 

3. SYSTEM DESCRIPTION 3-1 

4. PERFORMANCE EVALUATION TECHNIQUES 4-1 

5. PERFORMANCE ASSESSMENT 5-1 

5.1 Weather Conditions 5-2 

5.2 System Thermal Performance 5-4 

5.3 Subsystem Performance 5-9 

5.3.1 Collector Array and Storage Subsystem 5-9 

5.3.1.1 Collector Array 5-9 

5.3.1.2 Storage 5-12 

5.3.2 Domestic Hot Water (DHW) Subsystem 5-15 

5.3.3 Space Heating Subsystem 5-17 

5.4 Operating Energy 5-19 

5.5 Energy Savings 5-19 

6. REFERENCES 6-1 

APPENDIX A DEFINITIONS OF PERFORMANCE FACTORS AND SOLAR TERMS A-l 

APPENDIX B SOLAR ENERGY SYSTEM PERFORMANCE EQUATIONS B-l 

APPENDIX C LONG-TERM AVERAGE WEATHER CONDITIONS C-l 

APPENDIX D MONTHLY SOLAR ENERGY DISTRIBUTION FLOWCHARTS D-l 

APPENDIX E MONTHLY SOLAR ENERGY DISTRIBUTIONS E-l 



n 



LIST OF ILLUSTRATIONS 

FIGURES TITLE PAGE 

3-1 Solar Energy System Schematic 3-2 

5-1 Solar Energy Distribution Flowchart Summary 5-6 

D-l Solar Energy Distribution Flowchart - D-2 

November 1978 

D-2 Solar Energy Distribution Flowchart - D-3 

December 1978 

D-3 Solar Energy Distribution Flowchart - D-4 

January 1979 

D-4 Solar Energy Distribution Flowchart - D-5 

February 1979 

D-5 Solar Energy Distribution Flowchart - D-6 

March 1979 



m 



LIST OF TABLES 

TABLES TITLE PAGE 

5-1 Weather Conditions 5-3 

5-2 System Thermal Performance Summary 5-5 

5-3 Solar Energy Distribution Summary 5-7 

5-4 Solar Energy System Coefficient of Performance 5-8 

5-5 Collector Array Performance 5-10 

5-6 Storage Performance 5-13 

5-7 Solar Energy Losses - Storage and Transport 5-14 

5-8 Domestic Hot Water Subsystem Performance 5-16 

5-9 Space Heating Subsystem Performance 5-18 

5-10 Operating Energy 5-20 

5-11 Energy Savings 5-21 

E-l Solar Energy Distribution - E-2 

November 1978 

E-2 Solar Energy Distribution - E-3 

December 1978 

E-3 Solar Energy Distribution - E-4 

January 1979 

E-4 Solar Energy Distribution - E-5 

February 1979 

E-5 Solar Energy Distribution - E-6 

March 1979 " 



IV 



NATIONAL SOLAR DATA PROGRAM REPORTS 



Reports prepared for the National Solar Data Program are numbered under speci- 
fic format. For example, this report for the Montecito Pines project site is 
designated as SOLAR/1045-79/14. The elements of this designation are explained 
in the following illustration. 



SOLAR/1045-79/14 



Prepared for the 

National Solar 

Data Program 



Demonstration Site 



Report Type 
Designation 



Year 



o Demonstration Site Number: 

Each project site has its own discrete number - 1000 through 1999 for 
residential sites and 2000 through 2999 for commercial sites. 

o Report Type Designation: 

This number identifies the type of report, e.g., 

Monthly Performance Reports are designated by the numbers 01 (for 
January) through 12 (for December). 



Solar Energy System Performance Evaluations are designated by the 
number 14. 



Solar Project Descriptions are designated by the number 50. 

Solar Project Cost Reports are designated by the number 60. 

These reports are disseminated through the U. S. Department of Energy Technical 
Information Center, P. 0. Box 62, Oak Ridge, Tennessee 37830. 



VI 



1 . FOREWORD 

The National Program for Solar Heating and Cooling is being conducted by the 
Department of Energy under the Solar Heating and Cooling Demonstration Act of 
1974. The overall goal of this activity is to accelerate the establishment of 
a viable solar energy industry and to stimulate its growth to achieve a 
substantial reduction in nonrenewable energy resource consumption through 
widespread applications of solar heating and cooling technology. 

Information gathered through the Demonstration Program is disseminated in a 
series of site-specific reports. These reports are issued as appropriate and 
may include such topics as: 

o Solar Project Description 

o Design/Construction Report 

o Project Costs 

o Maintenance and Reliability 

o Operational Experience 

o Monthly Performance 

o System Performance Evaluation 

The International Business Machines (IBM) Corporation is contributing to the 
overall goal of the Demonstration Act by monitoring, analyzing, and reporting 
the thermal performance of solar energy systems through analysis of measure- 
ments obtained by the National Solar Data Program. 

The Solar Energy System Performance Evaluation Report is a product of the 
National Solar Data Program. Reports are issued periodically to document the 
results of analysis of specific solar energy system operational performance. 
This report includes system description, operational characteristics and 
capabilities, and an evaluation of actual versus expected performance. The 
Monthly Performance Report, which is the basis for the Solar Energy System 
Performance Evaluation Report, is published on a regular basis. Each parameter 
presented in these reports as characteristic of system performance represents 
over 8,000 discrete measurements obtained each month by the National Solar 



1-1 



Data Network (NSDN). Documents referenced in this report are listed in Section 
6, "References." Numbers shown in brackets refer to reference numbers in 
Section 6. All other documents issued by the National Solar Data Program for 
the Montecito Pines solar energy system are listed in Section 7, "Bibliography." 

This Solar Energy System Performance Evaluation Report presents the results of 
a thermal performance analysis of the Montecito Pines solar energy system. 
The analysis covers operation of the system from November 1978 through 
March 1979. The Montecito Pines solar energy system provides DHW preheating 
and space heating to an 8-unit apartment building located in Santa Rosa, 
California. Section 2 presents a summary of the overall system msults. A 
system description is contained in Section 3. Analysis of the system thermal 
performance was accomplished using a system energy balance technique described 
in Section 4. Section 5 presents a detailed assessment of the individual 
subsystems applicable to the site. 

The measurement data for the reporting period were collected by the NSDN [1]. 
System performance data are provided through the NSDN via an IBM-developed 
Central Data Processing System (CDPS) [2]. The CDPS supports the collection 
and analysis of solar data acquired from instrumented systems located through- 
out the country. This data is processed daily and summarized into monthly 
performance reports. These monthly reports form a common basis for system 
evaluation and are the source of the performance data used in this report. 



1-2 



2. SUMMARY AND CONCLUSIONS 

This section provides a summary of the performance of the solar energy system 
installed at Montecito Pines, located in Santa Rosa, California, for the period 
November 1978 through March 1979. This solar energy system is designed to 
support the domestic hot water and space heating loads. A detailed descrip- 
tion of Montecito Pines solar energy system operation is presented in Section 
3. 



2. 1 Performance Summary 

The solar energy site was occupied from November 1978 through March 1979, and 
the solar energy system operated continuously during this reporting period. 
The total incident solar energy was 159.15 million Btu, of which 45.96 mil- 
lion Btu were collected by the solar energy system. Solar energy satisfied 
48 percent of the DHW requirements and 10 percent of the space heating require- 
ments. The solar energy system provided a fossil fuel savings of 49.25 
million Btu at an expense of 2.47 million Btu of electrical energy. Solar 
energy applied to the DHW and space heating loads was 29.60 million Btu. 
Solar system losses were 16.13 million Btu. Energy cost of operating the solar 
system was 3.60 million Btu of electricity. 

2.2 Conclusions 

The Montecito Pines solar energy system has been remarkably trouble-free over 
the reporting period. The control system functioned according to design 
throughout the period ensuring stable system performance. Subsequent to 
January 20, 1979, unreasonable or unlikely excursions in the temperature and 
heat transfer fluid flow measurements of the space heating subsystem have 
occurred periodically necessitating software filtering of this data. In this 
report, the space heating load and the solar energy used to satisfy space 
heating requirements for the months of January, February and March were derived 
using extensively filtered data. 



2-1 



3. SYSTEM DESCRIPTION 

The Montecito Pines site is an apartment complex in Santa Rosa, California. 
It consists of one instrumented unit containing eight apartments. Each 
apartment has approximately 864 square feet of conditioned space. Solar 
energy is used for space heating and preheating domestic hot water (DHW). The 
solar energy system which serves the eight-apartment unit has an array of flat- 
plate collectors with a gross area of 950 square feet. The array faces 23 
degrees west of south at an angle of 45 degrees to the horizontal. Water is 
the transfer medium that delivers solar energy from the collector array to 
storage and to the space heating and hot water loads. Freeze protection is 
provided by drain-down. Solar energy is stored underground in a 2000-gallon 
insulated tank. City water is circulated through a heat exchanger in the 
storage tank for preheating before entering a gas-fired boiler which supplies 
DHW on demand. When solar energy is insufficient to satisfy the space heating 
load, the gas-fired boiler provides auxiliary energy for space heating. The 
system, shown schematically in Figure 3-1, has four modes of solar operation. 

Mode 1 - Collector-to-Storage : This mode activates when the collector plate 
temperature exceeds the storage temperature by 17°F and terminates when a 
temperature difference of 3°F is reached. Collector loop pump PI is operating. 

Mode 2 - Storage- to-Space Heating : This mode activates when there is a space 
heating demand and the temperature at the top of the storage tank is 105°F or 
higher. Space heating pump P2 is operating and mode diversion valves divert 
the flow to the heat exchanger in the storage tank, bypassing the gas-fired 
boiler. 

Mode 3 - Auxiliary Space Heating, DHW Preheating : This mode activates when 
there is a space heating demand and the temperature at the top of the storage 
tank is less than 105°F. Space heating pump P2 is operating and mode diversion 
valves direct the flow through the gas-fired boiler, bypassing the heat 
exchanger in the storage tank. 



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Mode 4 - DHW Preheating: This mode activates when there is a demand for DHW. 
Incoming city water passes through the heat exchanger in the storage tank on 
the way to the gas-fired boiler which supplies hot water, on demand, to the 
apartments. 



3-3 



4. PERFORMANCE EVALUATION TECHNIQUES 

The performance of the Montecito Pines solar energy system is evaluated by 
calculating a set of primary performance factors which are based on those 
proposed in the intergovernmental agency report "Thermal Data Requirements and 
Performance Evaluation Procedures for the National Solar Heating and Cooling 
Demonstration Program" [3]. These performance factors quantify the thermal 
performance of the system by measuring the amount of energies that are being 
transferred between the components of the system. The performance of the 
system can then be evaluated based on the efficiency of the system in trans- 
ferring these energies. All performance factors and their definitions are 
1 isted in Appendix A. 

Data from monitoring instrumentation located at key points within the solar 
energy system are collected by the National Solar Data Network. This data is 
first formed into factors showing the hourly performance of each system com- 
ponent, either by summation or averaging techniques, as appropriate. The 
hourly factors then serve as a basis for calculating the daily and monthly 
performance of each component subsystem. The performance factor equations for 
this site are listed in Appendix B. 

Each month, as appropriate, a summary of overall performance of the Montecito 
Pines site and a detailed subsystem analysis are published. These monthly 
reports for the period covered by this Solar Energy System Performance Evalua- 
tion (November 1978 through March 1979) are available from the Technical 
Information Center, Oak Ridge, Tennessee 37830. 

In the tables and figures in this report, an asterisk indicates that the 
value is not available for that month; N.A. indicates that the value is not 
applicable for this site. 



4-1 



5. PERFORMANCE ASSESSMENT 

The performance of the Montecito Pines solar energy system has been evaluated 
for the November 1978 through March 1979 time period. Two perspectives were 
taken in this assessment. The first views the overall system in which the 
total solar energy collected, the system load, the measured values for solar 
energy used, and system solar fraction are presented. Where applicable, the 
expected values for solar energy used and system solar fraction are also 
shown. The expected values have been derived from a modified f-chart analysis 
which uses measured weather and subsystem loads as input. The f-chart is a 
performance estimation technique used for designing solar heating systems. It 
was developed by the Solar Energy Laboratory, University of Wisconsin - Madison 
The system mode used in the analysis is based on manufacturer's data and other 
known system parameters. In addition, the solar energy system coefficient of 
performance (COP) at both the system and subsystem level has been presented. 

The second view presents a more in-depth look at the performance of individual 
subsystems. Details relating to the performance of the collector array and 
storage subsystems are presented first, followed by details pertaining to the 
space heating and domestic hot water (DHW) subsystems. Included in this 
section are all parameters pertinent to the operation of each individual 
subsystem. 

In addition to the overall system and subsystem analysis, this report also 
describes the equivalent energy savings contributed by the solar energy 
system. The overall system and individual subsystem energy savings are 
presented in Section 5.5. 

The performance assessment of any solar energy system is highly dependent on 
the prevailing weather conditions at the site during the period of performance. 
The original design of the system is generally based on the long-term averages 
for available insolation and temperature. Deviations from these long-term 
averages can significantly affect the performance of the system. Therefore, 



5-1 



before beginning the discussion of actual system performance, a presentation 
of the measured and long-term averages for critical weather parameters has 
been provided. 

5. 1 Weather Conditions 

Monthly values of the total solar energy incident in the plane of the col- 
lector array and the average outdoor temperature measured at the Montecito 
Pines site during the reporting period are presented in Table 5-1. Also 
presented in Table 5-1 are the corresponding long-term average monthly values 
of the measured weather parameters. These data are taken from Reference 
Monthly Environmental Data for Systems in the National Solar Data Networ k [4] . 
A complete yearly listing of these values for the site is given in Appendix C. 

During November 1978 through March 1979 the average daily total incident solar 
energy on the collector array was 1109 Btu per square foot per day. This was 
below the estimated average daily solar radiation for this geographical area 
during the reporting period of 1312 Btu per square foot per day for a south- 
facing plane with a tilt of 45 degrees to the horizontal. The average ambient 
temperature during November 1978 through March 1979 was 46°F as compared with 
the long-term average for November 1979 through March 1979 of 51 °F. The 
number of heating degree-days for the same period (based on a 65°F reference) 
was 2887, as compared with the summation of the long-term averages of 2191. The 
number of cooling degree-days for the same period (based on a 65°F reference) 
was zero, as compared with the summation of the long-term averages of zero. 

Monthly values of heating and cooling degree-days are derived from daily 
values of ambient temperature. They are useful indications of the system 
heating and cooling loads. Heating degree-days and cooling degree-days are 
computed as the difference between daily average temperature and 65°F. For 
example, if a day's average temperature was 60°F, then five heating degree- 
days are accumulated. Similarly, if a day's average temperature was 80°F, 
then 15 cooling degree-days are accumulated. The total number of heating and 
cooling degree-days is summed monthly. 



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5-3 



5.2 System Thermal Performance 

The thermal performance of a solar energy system is a function of the total 
solar energy collected and applied to the system load. The total system load 
is the sum of the useful energy delivered to the loads (excluding losses in 
the system), both solar and auxiliary thermal energies. The portion of the 
total load provided by solar energy is defined as the solar fraction of the 
load. 

The thermal performance of the Montecito Pines solar energy system is presented 
in Table 5-2. This performance assessment is based on the 5-month period from 
November 1978 to March 1979. During the reporting period, a total of 45.96 
million Btu of solar energy was collected and the total system load was 165.50 
million Btu. The measured amount of solar energy delivered to the load sub- 
system^) was 29.60 million Btu or 17.5 million Btu less than the expected 
value. The measured system solar fraction was 18 percent as compared to an 
expected value of 28 percent. 

Figure 5-1 illustrates the flow of solar energy from the point of collection 
to the various points of consumption and loss for the reporting period. The 
numerical values account for the quantity of energy corresponding with the 
transport, operation, and function of each major element in the Montecito 
Pines solar energy system for the total reporting period. 

Solar energy distribution flowcharts for each month of the reporting period 
are presented in Appendix D. 

Table 5-3 summarizes solar energy distribution and provides a percentage 
breakdown. For the period November 1978 through March 1979, the load subsystem(s) 
consumed 64 percent of the energy collected and 35 percent was lost. One per- 
cent of the collected energy is represented by solar energy storage gain. 
Appendix E contains the monthly solar energy percentage distributions. 

The solar energy coefficient of performance (COP) is indicated in Table 5-4. 
The COP simply provides a numerical value for the relationship of solar 



5-4 



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5-5 



FIGURE 5-1. SOLAR ENERGY (MILLION BTU) DISTRIBUTION FLOWCHART - SUMMARY 



Incident 
Solar Energv 




MONTECITO PINES 


Solar Encgv 
Storage Losses 


159.15 








5. 


4 








in 






Change in 
Stored Enerqy 








Operational 
Incident 
Solar Energy 




Transport Loss 
Collector to 
Storage 


ECSS Subsystem 
Operating Energy 








0.23 




139.48 






5.54 


2.47 




♦ 






1 
















i 
I 






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Solar Energy 








Solar Energy 
to Storage 


1 


Solar Energy 
liom Storage 










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id 


40.42 








35 05 








Transport Loss 
Collector to DHW 








Tro 'Sport Loss 

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Domestic Hot 
Water Solar 
Energy Used 


























N.A. 


16.29 






DHW Subsystem 
Operating Energy 




Domestic Hot 
Water Auxiliary 
Thermal Used 






3.42 


24.03 










Domestic Hot 
Water Load 










in 




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Transport Loss 
Collector to 
Space Heating 








Transport Loss 
Storage to 
Space Heati.Tg 


( 1 1 
















N.A. 








5.45 














Space Heating 
Solar Energy Used 


























N.A. 


13.31 






Space Heating 
Subsystem 
Operating Energy 




Space Heating 
Auxiliary Thermal 
Used 






10.72 


157.56 










Space Heating 
Load 










(i) 




131.31 














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Space Cooling 








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Space Coolmg 


















N.A. 








N.A. 














Space Cooling 
Solar Energy Used 


























N.A. 


N.A. 






Space Cooling 
Subsystem 
Operating Energy 




Space Cooling 
Auxiliary Thermal 
Used 










in 


N.A. 


N.A. 














Total Loss - 
Collector to 
Storage and Loads 






Space Cooling 
Load 




Total Loss - 
Storage to Loads 


















5.54 


N.A. 


5.45 





• Denotes Unavailable Data 

N A denotes not applicable data 

(II May contribute to offset of space heating load (if known - see text for discussion) 

5-6 



S002 



TABLE 5-3. SOLAR ENERGY DISTRIBUTION - SUMMARY OCTOBER 1978 THROUGH MARCH 1979 

MONTECITO PINES 

_4L_£| million Btu T0TA| _ S0LAR ENERQY C0LLECTED 
29.60 million Btu $0LAR ENERGy TQ LQADS 



64% 



16 .2 9 million Btu $0LAR ENERGY T0 DHW SUBSYSTEM 
35 7o 

lllion Btu SQLAR ENERGY T0 SPACE HEATING SUBSYSTEM 



29% 
N.A. million Btu 



% 
16.13 million Btu 



35% 



SOLAR ENERGY TO SPACE COOLING SUBSYSTEM 
OLAR ENERGY LOSSES 



5 14 million Btu s0| _ AR ENERGY L0SS FR0M STORAGE 
11 % 

1Q 99 million Btu SQLAR ENERGY L0SS IN TRANSPORT 
5.54 million Btu C0L| _ ECT0R TQ ST0RAGE L0SS 

I C lo 

N.A. million Btu C0LLECT0R TQ LQAD LQSS 



ill ion Btu- C0LLECT0R TG QHW lQS$ 



% 
N.A. million Btu 



% 
N.A. million Btu 



COLLECTOR TO SPACE HEATING LOSS 
COLLECTOR TO SPACE COOLING LOSS 



5.45 million Btu ST0RAGE TQ LQAD LQSS 



12 % 

mv ion Btu, 



% 

5.45 million Btu< 
12 % 

N.A. million Btu, 



STORAGE TO DHW LOSS 

STORAGE TO SPACE HEATING LOSS 

STORAGE TO SPACE COOLING LOSS 

lo 

0.23^ million Btu SQLAR ENERQY ST0RAGE CHANGE 
N.A. - Denotes not applicable data 5-7 



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energy collected or transported or used and the energy required to perform the 
transition. The greater the COP value, the more efficient the subsystem. The 
solar energy system at Montecito Pines functioned at a weighted average COP 
value of 8.22 for the reporting period November 1978 through March 1979. 

5.3 Subsystem Performance 

The Montecito Pines solar energy installation may be divided into three sub- 
systems: 

1. Collector Array and Storage 

2. Domestic Hot Water (DHW) 

3. Space Heating 

€ach subsystem is evaluated and analyzed by the techniques defined in Section 
4 to produce the monthly performance reports. This section presents the 
results of integrating the monthly data available on the three subsystems for 
the period November through March. 

5.3.1 Collector Array and Storage Subsystem 

5.3.1.1 Collector Array 

Collector array performance for the Montecito Pines site is presented in Table 
5-5. The total incident solar radiation on the collector array for the period 
November 1978 through March 1979 was 159.15 million Btu. During the period 
the collector loop was operating the total insolation amounted to 139.48 mil- 
lion Btu. The total collected solar energy for the period was 45.96 million 
Btu, resulting in a collector array efficiency of 29 percent, based on total 
incident insolation. Solar energy delivered from the collector array to 
storage was 40.42 million Btu. Energy loss during transfer from the collector 
array to storage was 5.54 million Btu. This loss represented 12 percent of 
the energy collected. Operating energy required by the collector loop was 
2.47 million Btu. 



5-9 



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5-10 



Collector array efficiency has been computed from two bases. The first 
assumes that the efficiency is based upon all available solar energy. This 
approach makes the operation of the control system part of array efficiency. 
For example, energy may be available at the collector, but the collector fluid 
temperature is below the control minimum; therefore, the energy is not col- 
lected. In this approach, collector array performance is described by comparing 
the collected solar energy to the incident solar energy. The ratio of these 
two energies represents the collector array efficiency which may be expressed 
as 

«c ■ V Q i 

where: n_ = collector array efficiency 

Q = collected solar energy 

Q- = incident solar energy 

The monthly efficiency computed by this method is listed in the column entitled 
"Collector Array Efficiency" in Table 5-5. 

The second approach assumes the efficiency is based upon the incident solar 
energy during the periods of collection only. 

Evaluating collector efficiency using operational incident energy and compen- 
sating for the difference between gross collector array area and the gross 
collector area yield operational collector efficiency. Operational collector 
efficiency, n , is computed as follows: 

"co = Q s /(Q oj x £) 
a 

where: Q = collected solar energy 

Q . = operational incident energy 



5-11 



A = gross collector area (product of the number 
of collectors and the total envelope area of 
one unit) 

A o = gross collector array area (total area perpen- 
a 

dicular to the solar flux vector, including all 
mounting, connecting and transport hardware) 

A 
Note: The ratio -^ is typically 1.0 for most collector array configurations. 

a 

The monthly efficiency computed by this method is listed in the column entitled 
"Operational Collector Array Efficiency" in Table 5-5. This latter efficiency 
term is not the same as collector efficiency as represented by the ASHRAE 
Standard 93-77 [5]. Both operational collector efficiency and the ASHRAE 
collector efficiency are defined as the ratio of actual useful energy collected 
to solar energy incident upon the collector and both use the same definition 
of collector area. However, the ASHRAE efficiency is determined from instan- 
taneous evaluation under tightly controlled, steady-state test conditions, 
while the operational collector efficiency is determined from the actual 
conditions of daily solar energy system operation. Measured monthly values of 
operational incident energy and computed values of operational collector 
efficiency are presented in Table 5-5. 

5.3.1.2 S torage 

Storage performance data for the Montecito Pines site for the reporting period 
is shown in Table 5-6. Results of analysis of solar energy losses during 
transport and storage are shown in Table 5-7. This table contains an evalua- 
tion of solar energy transport losses as a fraction of energy transported to 
subsystems. 

During the reporting period, total solar energy delivered to storage was 40.42 
million Btu. There were 35.05 million Btu delivered from storage to the 
DHW and space heating subsystems. Energy loss from storage was 5.14 million 



5-12 



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5-13 



TABLE 5-7. SOLAR ENERGY LOSSES - STORAGE 

MONTECITO PINES 



AND TRANSPORT 







MONTH 




NOV 


DEC 


JAN 


FFR 


MAR 






TOTAL 


1 


SOLAR ENERGY (SE) COLLECTED 
MINUS SE DIRECTLY TO LOADS 
(million Btu) 


10.04 


9.78 


7.55 


8.64 


9.95 






45.96 


2 


SE TO STORAGE 
(million Btu) 


8.34 


8.36 


6.98 


7.96 


8.78 






40.42 


3. 


LOSS COLLECTOR TO STORAGE (%) 
1 -2 

1 

CHANGE IN STORED ENERGY 
(million Btu) 


17 


15 


8 


8 


12 






12 


4. 


-0.03 


0.19 


-0.01 


-0.11 


0.19 






0.23 


5. 


SOLAR ENERGY - STORAGE TO 
DHW SUBSYSTEM (million Btu) 


1.65 


2.58 


3.33 


4.01 


4.72 






16.29 


| 6. 

1 


SOLAR ENERGY - STORAGE TO 
SPACE HEATING SUBSYSTEM 

(million Btu) 


5.49 


3.89 


2.70 


3.12 


3.56 






18.76 


: 7. 


SOLAR ENERGY - STORAGE TO 
SPACE COOLING SUBSYSTEM 

(million Btu) 


N.A. 


N.A. 


N.A. 


N.A. 


N.A. 






N.A. 


8. 


LOSS FROM STORAGE (%) 
2- (4 + 5+6 + 7) 
2 


15 


20 


14 


12 


4 






13 


9 

! 
! 


HOT WATER SOLAR ENERGY (HWSE) 
FROM STORAGE (million Btu) 


1.65 


2.58 


3.33 


4.01 


4.72 






16.29 


| 
| 1 0. 


LOSS - STORAGE TO HWSE (%) 
5-9 
5 
























I 
11. 


HEATING SOLAR ENERGY (HSE) 
FROM STORAGE 
(million Btu) 


3.30 


2.50 


2.00 


2.37 


3.14 






13.31 


12. 


LOSS - STORAGE TO HSE (%) 
6- 11 
6 


40 


36 


26 


24 


12 






29 



N.A. - Denotes not applicable data 



S002 



5-14 



Btu. This loss represented 13 percent of the energy delivered to storage. 
The storage efficiency was 87 percent: This is calculated as the ratio of the 
sum of the energy removed from storage and the change in stored energy, to the 
energy delivered to storage. The average storage temperature for the period 
was 101°F. 

Storage subsystem performance is evaluated by comparison of energy to storage, 
energy from storage, and the change in stored energy. The ratio of the sum of 
energy from storage and the change in stored energy, to the energy to storage 
is defined as storage efficiency, n . This relationship is expressed in the 
equation 

n = (aQ + Q )/Q • 
's y so si 

where: 

aQ = change in stored energy. This is the difference in 
the estimated stored energy during the specified 
reporting period, as indicated by the relative 
temperature of the storage medium (either positive 
or negative value) 

Q = energy from storage. This is the amount of energy 
extracted by the load subsystem from the primary 
storage medium 

Q •= energy to storage. This is the amount of energy 

(both solar and auxiliary) delivered to the primary 
storage medium 

5.3.2 Domestic Hot Water (DHW) Subsystem 

The DHW subsystem performance for the Montecito Pines site for the reporting 
period is shown in Table 5-8. The DHW subsystem consumed 16.29 million Btu of 



5-15 



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5-16 



solar energy and 30.06 million Btu of auxiliary fossil fuel energy to satisfy 
a hot water load of 34.23 million Btu. The solar fraction of this load was 
48 percent. 

A common gas-fired boiler provides the auxiliary thermal energy for both the 
DHW and space heating subsystems. The performance of the DHW subsystem is 
described by comparing the amount of solar energy supplied to the subsystem 
with the total energy required by the subsystem. The total energy required by 
the subsystem consists of both solar energy and auxiliary thermal energy. The 
DHW load is defined as the amount of energy required to raise the mass of 
water delivered by the DHW subsystem between the temperature at which it 
entered the subsystem and its delivery temperature. The DHW solar fraction is 
defined as the portion of the DHW load which is supported by solar energy. 

5.3.3 Space Heating Subsystem 

The space heating subsystem performance for the Montecito Pines site for the 
reporting period is shown in Table 5-9. The space heating subsystem consumed 
13.31 million Btu of solar energy and 196.95 million Btu of auxiliary fossil 
fuel energy to satisfy a space heating load of 131.31 million Btu. The solar 
fraction of this load was 10 percent. 

Note that the sum of the solar energy and the auxiliary thermal energy for the 
reporting period exceeds the space heating load by 39.56 million Btu. This 
subsystem loss is attributable primarily to the maintenance of a boiler 
temperature in the range of 130°F to 1'40°F during periods when solar energy 
was satisfying the space heating load and during periods of no space heating 
load. 

The performance of the space heating subsystem is described by comparing the 
amount of solar energy supplied to the subsystem with the energy required to 
satisfy the total space heating load. The energy required to satisfy the 
total load consists of both solar energy and auxiliary thermal energy. The 
ratio of solar energy supplied to the load to the total load is defined as the 
heating solar fraction. 



5-17 



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5-18 



5.4 Operating Energy 

Measured values of the Montecito Pines solar energy system and subsystem 
operating energy for the reporting period are presented in Table 5-10. A 
total of 16.61 million Btu of operating energy was consumed by the entire 
system during the reporting period. 

Operating energy for a solar energy system is defined as the amount of elec- 
trical energy required to support the subsystems without affecting their 
thermal state. 

Total system operating energy for Montecito Pines is the energy required to 
support the energy collection and storage subsystem (ECSS), the DHW subsystem, 
and the space heating subsystem. With reference to the system schematic 
(Figure 3-1), the ECSS operating energy consists of pump PI (EP100). The DHW 
subsystem operating energy consists of pump P3 (EP300) and boiler circulation 
loop pump P4 (EP301). The space heating subsystem operating energy consists 
of pump P2 (EP400). 

5.5 Energy Savings 

Energy savings for the Montecito Pines site for the reporting period are 
presented in Table 5-11. For this period the total savings of fossil fuel 
energy were 49.25 million Btu, for a monthly average of 9.85 million Btu. An 
electrical energy expense of 2.47 million Btu was incurred during the reporting 
period for the operation of solar energy transportation pump EP100. 

Solar energy system savings are realized whenever energy provided by the solar 
energy system is used to meet system demands which would otherwise be met by 
auxiliary energy sources. The operating energy required to provide solar 
energy to the load subsystems is subtracted from the solar energy contribution 
to determine net savings. Note that the only operating energy used that is 
attributable to the solar energy system is the collector loop pump PI (EP100). 



5-19 



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2.18 
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0.69 
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5-21 



The auxiliary source at Montecito Pines consists of a gas-fired boiler which 
provides auxiliary thermal energy to both the DHW and space heating subsystems 
This unit is considered to be 80 percent efficient for computational purposes. 



5-22 



6. REFERENCES 

1. U.S. Department of Energy, National Solar Data Network , prepared 
under contract number EG-77-C-4049 by IBM Corporation, 
December 1977. 

2. J. T. Smok, V. S. Sohoni , J. M. Nash, "Processing of Instrumented 
Data for the National Solar Heating and Cooling Demonstration 
Program," Conference on Performance Monitoring Techniques for 
Evaluation of Solar Heating and Cooling Systems, Washington, D.C., 
April 1978. 

3. E. Streed, et. al., Thermal Data Requirements and Performance 
Evaluation Procedures for the National Solar Heating and Cooling 
Demonstration Program , NBSIR-76-1137, National Bureau of Standards, 
Washington, D.C. , 1976. 

4. Mears, J. C. Reference Monthly Environmental Data for Systems in 
the National Solar Data Network . Department of Energy report 
SOLAR/0019-79/36. Washington, D.C, 1979. 

5. ASHRAE Standard 93-77 , Methods of Testing to Determine the Thermal 
Performance of Solar Collectors , The American Society of Heating, 
Refrigeration and Air Conditioning Engineers, Inc., New York, N.Y., 
1977. 

6.# Monthly Performance Report , Montecito Pines , SOLAR/1045-78/11 , 
Department of Energy, Washington, D.C, (November 1978). 

7.# Monthly Performance Report , Montecito Pines , SOLAR/1045-78/12, 
Department of Energy, Washington, D.C, (December 1978). 

8.# Monthly Performance Report , Montecito Pines , SOLAR/1045-79/01 , 
Department of Energy, Washington, D.C, (January 1979). 

9.# Monthly Performance Report , Montecito Pines , SOLAR/1045-79/02, 
Department of Energy, Washington, D.C, (February 1979). 

10. # Monthly Performance Report , Montecito Pines , SOLAR/1045-79/03, 
Department of Energy, Washington, D.C, (March 1979). 



#Copies of these reports may be obtained from Technical Information Center, 
0. Box 62, Oak Ridge, Tennessee 37830. 

6-1 



APPENDIX A 
DEFINITIONS OF PERFORMANCE FACTORS AND SOLAR TERMS 



COLLECTOR ARRAY PERFORMANCE 

The collector array performance is characterized by the amount of solar 
energy collected with respect to the energy available to be collected. 

o INCIDENT SOLAR ENERGY (SEA) is the total insolation available 
on the gross collector array area. This is the area of the 
collector array energy-receiving aperture, including the 
framework which is an integral part of the collector structure. 

o OPERATIONAL INCIDENT ENERGY (SEOP) is the amount of solar energy 
incident on the collector array during the time that the col- 
lector loop is active (attempting to collect energy). 

o COLLECTED SOLAR ENERGY (SECA) is the thermal energy removed 
from the collector array by the energy transport medium. 

o COLLECTOR ARRAY EFFICIENCY (CAREF) is the ratio of the energy 
collected to the total solar energy incident on the collector 
array. It should be emphasized that this efficiency factor is 
for the collector array, and available energy includes the 
energy incident on the array when the collector loop is inac- 
tive. This efficiency must not be confused with the more 
common collector efficiency figures which are determined from 
instantaneous test data obtained during steady-state operation 
of a single collector unit. These efficiency figures are often 
provided by collector manufacturers or presented in technical 
journals to characterize the functional capability of a partic- 
ular collector design. In general, the collector panel maximum 
efficiency factor will be significantly higher than the col- 
lector array efficiency reported here. 

STORAGE PERFORMANCE 

The storage performance is characterized by the relationships among the 
energy delivered to storage, removed from storage, and the subsequent 
change in the amount of stored energy. 

o ENERGY TO STORAGE (STEI) is the amount of energy, both solar 
and auxiliary, delivered to the primary storage medium. 

o ENERGY FROM STORAGE (STEO) is the amount of energy extracted 
by the load subsystems from the primary storage medium. 



A-l 



o CHANGE IN STORED ENERGY (STECH) is the difference in the estimated 

stored energy during the specified reporting period, as indicated 

by the relative temperature of the storage medium (either posi- 
tive or negative value). 

o STORAGE AVERAGE TEMPERATURE (TST) is the mass-weighted average 
temperature of the primary storage medium. 

o STORAGE EFFICIENCY (STEFF) is the ratio of the sum of the energy 
removed from storage and the change in stored energy to the 
energy delivered to storage. 

ENERGY COLLECTION AND STORAGE SUBSYSTEM 

The Energy Collection and Storage Subsystem (ECSS) is composed of the 
collector array, the primary storage medium, the transport loops between 
these, and other components in the system design which are necessary to 
mechanize the collector and storage equipment. 

o INCIDE NT SOLAR ENERGY (SEA) is the total insolation available 
on the gross collector array area. This is the area of the 
collector array energy-receiving aperture, including the frame- 
work which is an integral part of the collector structure. 

o AMBIENT TEMPERATURE (TA) is the average temperature of the out- 
door environment at the site. 

o ENERGY TO LOADS (SEL) is the total thermal energy transported 
from the ECSS to all load subsystems. 

o AUXILIARY THERMAL ENERGY TO ECSS (CSAUX) is the total auxiliary 
energy supplied to the ECSS, including auxiliary energy added to 
the storage tank, heating devices on the collectors for freeze- 
protection, etc. 

o ECSS OPERATING ENERGY (CSOPE) is the critical operating energy 
required to support the ECSS heat transfer loops. 

HOT WATER SUBSYSTEM 

The hot water subsystem is characterized by a complete accounting of the 
energy flow into and from the subsystem, as well as an accounting of 
internal energy. The energy into the subsystem is composed of auxiliary 
fossil fuel, and electrical auxiliary thermal energy, and the operating 
energy for the subsystem. 

o HOT WATER LOAD (HWL) is the amount of energy required to heat 
the amount of hot water demanded at the site from the incoming 
temperature to the desired outlet temperature. 



A-2 









o SOLAR FRACTION OF LOAD (HWSFR) is the percentage of the load 
demand which is supported by solar energy. 

o SOLAR ENERGY USED (HWSE) is the amount of solar energy supplied 
to the hot water subsystem. 

o OPERATING ENERGY (HWOPE) is the amount of electrical energy 
required to support the subsystem, (e.g., fans, pumps, etc.) 
and which is not intended to directly affect the thermal state 
of the subsystem. 

o AUXILIARY THERMAL USED (HWAT) is the amount of energy supplied 
to the major components of the subsystem in the form of thermal 
energy in a heat transfer fluid, or its equivalent. This term 
also includes the converted electrical and fossil fuel energy 
supplied to the subsystem. 

o AUXILIARY FOSSIL FUEL (HWAF) is the amount of- fossil fuel energy 
supplied directly to the subsystem. 

o ELECTRICAL ENERGY SAVINGS (HWSVE) is the estimated difference 
between the electrical energy requirements of an alternative 
conventional system (carrying the full load) and the actual 
electrical energy required by the subsystem. 

o FOSSIL FUEL SAVINGS (HWSVF) is the estimated difference between 
the fossil fuel energy requirements of the alternative conven- 
tional system (carrying the full load) and the actual fossil 
fuel energy requirements of the subsystem. 

SPACE HEATING SUBSYSTEM 

The space heating subsystem is characterized by performance factors account- 
ing for the complete energy flow into the subsystem. The average building 
temperature is tabulated to indicate the relative performance of the 
subsystem in satisfying the space heating load and in controlling the tem- 
perature of the conditioned space. 

o SPACE HEATING LOAD (HL) is the sensible energy added to the 
air in the building. 

o SOLAR FRACTION OF LOAD (HSFR) is the fraction of the sensible 
energy added to the air in the building derived from the solar 
energy system. 

o SOLAR ENERGY USED (HSE) is the amount of solar energy supplied 
to the space heating subsystem. 



A- 3 



OPERATING ENERGY (HOPE) is the amount of electrical energy 
required to support the subsystem, (e.g., fans, pumps, etc.) 
and which is not intended to directly affect the thermal state 
of the system. 

AUXILIARY THERMAL USED (HAT) is the amount of energy supplied 
to the major components of the subsystem in the form of thermal 
energy in a heat transfer fluid or its equivalent. This term 
also includes the converted electrical and fossil fuel energy 
supplied to the subsystem. 

AUXILIARY ELECTRICAL FUEL (HAE) is the amount of electrical 
energy supplied directly to the subsystem. 

ELECTRICAL ENERGY SAVINGS (HSVE) is the estimated difference 
between the electrical energy requirements of an alternative 
conventional system (carrying the full load) and the actual 
electrical energy required by the subsystem. 

BUILDING TEMPERATURE (TB) is the average heated space dry bulb 
temperature. 



A-4 



APPENDIX B 
SOLAR ENERGY SYSTEM PERFORMANCE EQUATIONS 
MONTECITO PINES 



INTRODUCTION 

Solar energy system performance is evaluated by performing energy balance 
calculations on the system and its major subsystems. These calculations 
are based on physical measurement data taken from each sensor every 
320 seconds. This data is then mathematically combined to determine the 
hourly, daily, and monthly performance of the system. This appendix 
describes the general computational methods and the specific energy 
balance equations used for this site. 

Data samples from the system measurements are integrated to provide 
discrete approximations of the continuous functions which characterize 
the system's dynamic behavior. This integration is performed by summation 
of the product of the measured rate of the appropriate performance para- 
meters and the sampling interval over the total time period of interest. 

There are several general forms of integration equations which are 
applied to each site. These general forms are exemplified as follows: 
The total solar energy available to the collector array is given by 

SOLAR ENERGY AVAILABLE = (1/60) Z [1001 x AREA] x At 

where 1001 is the solar radiation measurement provided by the pyranometer 
in Btu per square foot per hour, AREA is the area of the collector array 
in square feet, Ax is the sampling interval in minutes, and the factor 
(1/60) is included to correct the solar radiation "rate" to the proper 
units of time. 

Similarly, the energy flow within a system is given typically by 

COLLECTED SOLAR ENERGY = E [Ml 00 x AH] x Ax 

where M100 is the mass flow rate of the heat transfer fluid in lb /min and 
AH is the enthalpy change, in Btu/lb , of the fluid as it passes through 
the heat exchanging component. 

For a liquid system aH is generally given by 

AH = <L AT 
P 

where C is the average specific heat, in Btu/(lb -°F), of the heat trans- 
fer flu^d and AT, in °F, is the temperature differential across the heat 
exchanging component. 



B-l 



For an air system aH is generally given by 

AH = H (T .) - H (T. ) 
a v out' a v in' 

where H (T) is the enthalpy, in Btu/lb , of the transport air evaluated 
at the inlet and outlet temperatures of the heat exchanging component. 

H (T) can have various forms, depending on whether or not the humidity 
ratio of the transport air remains constant as it passes through the heat 
exchanging component. 

For electrical power, a general example is 

ECSS OPERATING ENERGY = (3413/60) E [EP100] x At 

where EP100 is the power required by electrical equipment in kilowatts 
and the two factors (1/60) and 3413 correct the data to Btu/min. 

These equations are comparable to those specified in "Thermal Data 
Requirements and Performance Evaluation Procedures for the National Solar 
Heating and Cooling Demonstration Program." This document was prepared 
by an interagency committee of the Government, and presents guidelines 
for thermal performance evaluation. 

Performance factors are computed for each hour of the day. Each integra- 
tion process, therfore, is performed over a period of one hour. Since 
long-term performance data is desired, it is necessary to build these 
hourly performance factors to daily values. This is accomplished, for 
energy parameters, by summing the 24 hourly values. For temperatures, 
the hourly values are averaged. Certain special factors, such as effi- 
ciencies, require appropriate handling to properly weight each hourly 
sample for the daily value computation. Similar procedures are required 
to convert daily values to monthly values. 



B-2 



EQUATIONS USED TO GENERATE MONTHLY PERFORMANCE VALUES 

NOTE: SENSOR IDENTIFICATION (MEASUREMENT) NUMBERS REFERENCE SYSTEM 
SCHEMATIC FIGURE 3-1 



AVERAGE AMBIENT TEMPERATURE (°F) 

TA = (1/60) x Z T001 x At 
AVERAGE BUILDING TEMPERATURE (°F) 

TB = (1/60) x Z [(T601 + T602 + T603 + T60' + T605 + T606 + T607 + T608)/8] x Ax 
DAYTIME AVERAGE AMBIENT TEMPERATURE (°F) 

TDA = (1/360) x I T001 x At 

FOR + 3 HOURS FROM SOLAR NOON 
HOT WATER LOAD (BTU) 

HWL = E [M300 x HWD (T304, T300)] x At 
SOLAR ENERGY TO DHW TANK (BTU) 

HWSE = Z [M300 x HWD (T302, T300)] x At 
INCIDENT SOLAR ENERGY PER SQUARE FOOT (BTU/FT 2 ) 

SE = (1/60) x Z 1001 x At 
INCIDENT SOLAR ENERGY ON COLLECTOR ARRAY (BTU) 

SEA = SE x CLAREA 
OPERATIONAL INCIDENT SOLAR ENERGY (BTU) 

SEOP = (1/60) x z [1001 x CLAREA] x At 
WHEN THE COLLECTOR LOOP IS ACTIVE 
SOLAR ENERGY COLLECTED BY THE ARRAY (BTU) 

SECA = Z [M100 x HWD (T101, T100)] x At 
COLLECTOR ARRAY EFFICIENCY 

CAREF = SECA/SEA 



B-3 



SOLAR ENERGY DELIVERED TO STORAGE (BTU) 

STEI = E [MIOO x HWD (T103, T102)] x At 
SOLAR ENERGY FROM STORAGE (BTU) 

STEO = E [M400 x HWD (T302, T301 ) + M300 x HWD (T302, T300)] x Ax 
WHEN SYSTEM IS IN THE STORAGE-TO-SPACE HEATING MODE 

STEO = Z [M300 x HWD (T302, T300)] x At 

WHEN SYSTEM IS IN THE CONVENTIONAL SPACE HEATING MODE 
AVERAGE TEMPERATURE OF STORAGE (°F) 

TST = (1/60) x E [(T200 + T201 + T202)/3] x At 
ECSS OPERATING ENERGY (BTU) 

CSOPE = 56.8833 x E EP100 x At 
HOT WATER SUBSYSTEM OPERATING ENERGY (BTU) 

HWOPE = 56.8833 x E (EP300 + EP301 ) x At 
SPACE HEATING SUBSYSTEM OPERATING ENERGY (BTU) 

HOPE = 56.86832 x E EP400 x At 
SERVICE HOT WATER TEMPERATURE (°F) 

THW = (1/60) x z T304 x At 

WHEN WATER IS BEING DRAWN 
SERVICE SUPPLY WATER TEMPERATURE (°F) 

TSW = (1/60) x Z T300 x At 

WHEN WATER IS BEING DRAWN 
AUXILIARY FOSSIL FUEL ENERGY TO LOADS (BTU) 

AXF = 1050 x Z (F400 - F400 ) 

WHERE REFERS TO A PRIOR REFERENCE VALUE 
P 

AUXILIARY THERMAL ENERGY TO LOADS 
AXT = 0.8 x AXF 



B-4 



SPACE HEATING AUXILIARY THERMAL ENERGY (BTU) 

HAT = AXT x HRATIO 

WHERE HRATIO = (HL - HSE)/[(HL - HSE) + (HWL - HWSE)] 
COLLECTED SOLAR ENERGY (BTU) 

SEC = SECA/CLAREA 
CHANGE IN STORED ENERGY (BTU) 

STECH = STOCAP x (STECH1 - STECH1 ) 

WHERE THE SUBSCRIPT REFERS TO A PRIOR REFERENCE VALUE 

P 

ENERGY DELIVERED TO LOAD SUBSYSTEMS FROM ECSS (BTU) 

CSEO = STEO 
STORING EFFICIENCY 

STEFF = (STECH + STEO)/STEI 
ECSS SOLAR CONVERSION EFFICIENCY 

CSCEF = SEL/SEA 
DHW SUBSYSTEM AUXILIARY THERMAL ENERGY (BTU) 

HWAT = AXT x HWRATIO 

WHERE HWRATIO = 1 - HRATIO 
DHW SUBSYSTEM AUXILIARY FOSSIL FUEL ENERGY 

HWAF = AXF x HWRATIO 
DHW SUBSYSTEM SOLAR FRACTION (PERCENT) 

HWSFR = 100 x HWSE/HWL 
HOT WATER CONSUMED 

HWCSM = W300 

WHERE W300 IS A TOTALIZING WATER METER WITH RANGE to 100 GALLONS 
DHW SUBSYSTEM FOSSIL FUEL ENERGY SAVINGS 

HWSVF = HWSE/0.6 



B-5 



SOLAR ENERGY TO SPACE HEATING SUBSYSTEM (BTU) 

HSE = I [M400 x HWD (T400, T401)] x At 

WHEN SYSTEM IS IN THE STORAGE-TO-SPACE HEATING MODE 
SPACE HEATING SUBSYSTEM LOAD (BTU) 

HL = v [M400 x HWD (T400, T401)] x At 
SPACE HEATING SUBSYSTEM FOSSIL FUEL ENERGY SAVINGS (BTU) 

HSVF = HSE/0.6 
SYSTEM LOAD 

SYSL = HL + HWL 
SOLAR ENERGY TO LOAD 

SEL = HWSE + HSE 
SPACE HEATING SUBSYSTEM SOLAR FRACTION 

HSFR = 100 x (HSE/HL) 
SOLAR FRACTION OF SYSTEM LOAD 

SFR = (HL x HSFR + HWL x HWSFR)/SYSL 
SYSTEM OPERATING ENERGY 

SYSOPE = HWOPE + HOPE + CSOPE 
TOTAL ENERGY CONSUMED 

TECSM = SYSOPE + AXF + SECA 
TOTAL ELECTRICAL ENERGY SAVINGS 

TSVE = CSOPE 
SYSTEM PERFORMANCE FACTOR 

SYSPF = SYSL/(AXF + 3.33 x SYSOPE) 
TOTAL FOSSIL ENERGY SAVINGS 

TSVF = HWSVF + HSVF 



B-6 



APPENDIX C 
LONG-TERM AVERAGE WEATHER CONDITIONS 



This appendix contains a table which lists the long-term average weather 
conditions for each month of the year for this site. 



C-l 



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C-2 



APPENDIX D 
MONTHLY SOLAR ENERGY DISTRIBUTION FLOWCHARTS 



The flowcharts in this appendix depict the quantity of solar energy corre- 
sponding to each major component or characteristic of the Montecito Pines 
solar energy system for 6 months of the reporting period. Each monthly 
flowchart represents a solar energy balance as the total input equals the 
total output. 



D-l 



FIGURE D-l. SOLAR ENERGY (MILLION BTU) DISTRIBUTION FLOWCHART - NOVEMBER 1978 



Incident 
Solar Energy 




MONTECITO PINES 


Solar Energy 
Storage Losses 


i 


35.06 








1.23 












ni 






Change in 
Stored Energy 










Operational 
Incident 
Solar Energy 




Transport Loss 
Collector to 
Storage 


ECSS Subsystem 
Operating Energy 












-0.03 










31.70 


1.70 


0.56 




♦ 






~r 
















i 
1 








Collected 
Solar Energy 








Solar Energy 
to Storage 


1 


Solar Energy 
Irom Storage 














10.04 






in 


8.34 






•ii 


7.14 










Transport Loss 
Collector to DHW 








Tiansport Loss 
Storage to OHW 
















N.A. 





















Domestic Hot 
Water Solar 
Energy Used 






















N.A. 


1.65 




DHW Subsystem 
Operating Energy 




Domestic Hot 
Water Auxiliary 
Thermal Used 




0.70 


4.93 








Domestic Hot 
Water Load 








in 




5.28 






id 






Transport Loss 
Collector to 
Space Heating 








Transport Loss 
Storage to 
Space Heating 












N.A. 








2.19 












Space Heating 
Solar Energy Used 






















N.A. I 3.30 




Space Heating 
Subsystem 
Operating Energy 




Space Heating 
Auxiliary Thermal 
Used 




2.22 


23.70 








Space Heating 
Load 








m 




19.53 












Transport Loss 
Collector to 
Space Cooling 








Transport Loss 
Storage to 
Space Cooling 














N.A. 








N.A. 












Space Cooling 
Solar Energy Used 




























Space Cooling 
Subsystem 
Operating Energy 




Space Cooling 
Auxiliary Thermal 
Used 








m 


N.A. 














Total Loss - 
Collector to 
Storage and Loads 






Space Cooling 
Load 




Total Loss - 
Storage to Loads 


















1.70 




2.19 





111 



* Denotes Unavailable Data 

N A denotes not applicable data 

(1) May contribute to offset of space heating Ipad (if known - see text for discussion) 



SOW 



D-2 



FIGURE D-2. SOLAR ENERGY (MILLION BTU) DISTRIBUTION FLOWCHART - DECEMBER 1978 



Incident 
Solar Energy 




MONTECITO PINES 


Solar Energy 
Storage Losses 


34.93 








1.70 


< 


1 






id 






Change in 
Stored Energy 








Operational 
Incident 
Solar Energy 




Transport Loss 
Collector to 
Storage 


ECSS Subsystem 
Operating Energy 












0.19 










31.43 


1.42 


0.56 




♦ 








1 
















i 
1 






Collected 
Solar Energy 








Solar Energy 
to Storage 


i 


Solar Energy 
from Storage 










9.78 






id 


8.36 








6.47 








Transport Loss 
Collector to DHW 








Transport Loss 
Storage to DHW 




















N.A. 























Domestic Hot 
Water Solar 
Energy Used 


























N.A. 


2.58 






DHW Subsystem 
Operating Energy 




Domestic Hot 
Water Auxiliary 
Thermal Used 






0.70 


4.32 










Domestic Hot 
Water Load 










id 




5.98 














Transport Loss 
Collector to 
Space Heating 








Transport Loss 
Storage to 
Space Heating 


1 1 1 
















N.A. 








1.39 














Space Heating 
Solar Energy Used 


























N.A. 


2.50 






Space Heating 
Subsystem 
Operating Energy 




Space Heating 
Auxiliary Thermal 
Used 






2.20 


37.60 










Space Heating 
Load 










(i) 




30.02 














Transport Loss 
Collector to 
Space Cooling 








Transport Loss 
Storage to 
Space Cooling 


















N.A. 








N.A. 














Space Cooling 
Solar Energy Used 


























N.A. 


N.A. 






Space Cooling 
Subsystem 
Operating Energy 




Space Cooling 
Auxiliary Thermal 
Used 










id 


N.A. 


N.A. 














Total Loss - 
Collector to 
Storage and Loads 






Space Cooling 
Load 




Total Loss - 
Storage to Loads 


















1.42 


N.A. 


1.39 





(II 



* Denotes Unavailable Data 

N.A. denotes not applicable data 

(1 ) May contribute to offset of space heating Ipad (if known - see text for discussion) 



$002 



D-3 



FIGURE D-3. 



SOLAR ENERGY (MILLION BTU) DISTRIBUTION FLOWCHART - JANUARY 1979 

MONTECITO PINES 



Incident 
Solar Energy 






Solar Energy 
Storage Losses 


26.38 








0.96 


1 


i 






d) 






Change in 
Stored Energy 








Operational 
Incident 
Solar Energy 




Transport Loss 
Collector to 
Storage 


ECSS Subsystem 
Operating Energy 








-0.01 




22.57 






0.57 


0.41 




♦ 








i 
















i 
1 






Collected 
Solar Energy 








Solar Energy 
to Storage 


1 


Solar Energy 
from Storage 










7.55 






in 


6.98 






i ii 


6 03 








Transport Loss 
Collector to DHW 








Transport Loss 
Storage to DHW 


















N.A. 























Domestic Hot 
Water Solar 
Energy Used 


























N.A. 


3.33 






DHW Subsystem 
Operating Energy 




Domestic Hot 
Water Auxiliary 
Thermal Used 






0.69 


4.67 










Domestic Hot 
Water Load 










in 




6.71 














Transport Loss 
Collector to 
Space Heating 








Transport Loss 
Storage to 
Space Heating 


















N.A. 








0.70 














Space Heating 
Solar Energy Used 


























N.A. 


2.00 






Space Heating 
Subsystem 
Operating Energy 




Space Heating 
Auxiliary Thermal 
Used 






2.18 


36.20 










Space Heating 
Load 










in 




28.96 














Transport Loss 
Collector to 
Space Cooling 








Transport Loss 
Storage to 
Space Cooling 


















N.A. 








N.A. 














Space Cooling 
Solar Energy Used 


























N.A. 


N.A. 






Space Cooling 
Subsystem 
Operating Energy 




Space Cooling 
Auxiliary Thermal 
Used 










id 


N.A. 


N.A. 














Total Loss - 
Collector to 
Storage and Loads 






Space Cooling 
Load 




Total Loss - 
Storage to Loads 


















0.57 


N.A. 


0.70 





111 






* Denotes Unavailable Data 

N.A, denotes not applicable data 

(1) May contribute to offset of space heating Ipad (if known - see text for discussion) 



S002 



'-4 



FIGURE D-4. SOLAR ENERGY (MILLION BTU) DISTRIBUTION FLOWCHART - FEBRUARY 1979 



Incident 
Solar Energy 




in 


MONTECITO PINES 


Solar Energy 
Storage Losses 


28.52 








0.94 














Change in 
Stored Energy 








Operational 
Incident 
Solar Energy 




Transport Loss 
Collector to 
Storage 


ECSS Subsystem 
Operating Energy 








-0.11 




24.84 






0.68 


0.44 




♦ 








i 














i 
I 






Collected 
Solar Energy 








Solar Energy 
to Storage 


1 


Solar Energy 
Irom Storage 






in 






8.64 






7.96 






in 


7.13 








Transport Loss 
Collector to DHW 








Tiansport Loss 
Storage to DHW 


















N.A. 





















Domestic Hot 
Water Solar 
Energy Used 














in 














N.A.I 4.01 






DHW Subsystem 
Operating Energy 




Domest c Hot 
Water Auxiliary 
Thermal Used 






0.63 


4.64 










Domestic Hot 
Water Load 












7.25 






in 








Transport Loss 
Collector to 
Space Heating 








Transport Loss 
Stcage to 
Space Heating 














N.A. 








0.75 












Space Heating 
Solar Energy Usea 














(D 






N.A. 


2.37 








Space Heating 
Subsystem 
Operating Energy 




Space Heating 
Auxiliary Thermal 
Used 






1.96 


31.75 










Space Heating 
Load 












25.82 














Transport Loss 
Collector to 
Space Cooling 








Transport Loss 
Storage to 
Space Cooling 


















N.A. 








N.A. 












Space Cooling 
Solar Energy Used 














id 














N.A. 


N.A. 






Space Cooling 
Subsystem 
Operating Energy 




Space Cooling 
Auxiliary Thermal 
Used 










N.A. 


N.A. 














Total Loss - 
Collector to 
Storage and Loads 






Space Cooling 
Load 




Total Loss - 
Storage to Loads 


















0.68 


N.A. 


0.75 





(11 



* Denotes Unavailable Data 

N A denotes not applicable data 

1 1 1 May contribute to offset of space heating Ipad (if known - see text for discussion) 



S002 



D-5 



FIGURE D-5. SOLAR ENERGY (MILLION BTU) DISTRIBUTION FLOWCHART - MARCH 1979 



Incident 
Solar Energv 






Solar Energy 
Storage Losses 


i 


34.26 








0.31 






i 






id 






Change in 
Stored Energy 










Operational 
Incident 
Solar Energy 




Transport Loss 
Collector to 
Storage 


ECSS Subsystem 
Operating Energy 












0.19 










28.94 


1.17 


0.50 




♦ 
























i 
1 

1 








Collected 
Solar Energv 








Solar Energy 
to Storage 


Solar Energy 
from Storage 














9.95 






id 


8.78 








8.28 










Transport Loss 
Collector to DHW 








Transport Loss 
Storage to DHW 


1 1 1 


















N.A. 























Domestic Hot 
Water Solar 
Energy Used 


























N.A. 


4.72 






DHW Subsystem 
Operating Energy 




Domestic Hot 

Water Auxiliary 
Thermal Used 






0.70 


5.47 










Domestic Hot 
Water Load 










in 




9.01 






in 








Transport Loss 
Collector to 
Space Heating 








Transport Loss 
Storage to 
Space Heating 
















N.A. 








0.42 














Space Heating 
Solar Energy Used 


























N.A. 


3.14 






Space Heating 
Subsystem 
Operating Energy 




Space Heating 
Auxiliary Thermal 
Used 






2.16 


28.31 










Space Heating 
Load 










d) 




26.98 














Transport Loss 
Collector to 
Space Cooling 








Transport Loss 
Storage to 
Space Cooling 


















N.A. 








N.A. 














Space Cooling 
Solar Energy Used 


























N.A. 


N.A. 






Space Cooling 
Subsystem 
Operating Energy 




Space Cooling 
Auxiliary Thermal 
Used 










(ii 


N.A. 


N.A. 














Total Loss - 
Collector to 
Storage and Loads 






Space Cooling 
Load 




Total Loss - 
Storage to Loads 


















1.17 


N.A. 


0.42 





(II 






* Denotes Unavailable Data 

N.A denotes not applicable data 

(II May contribute to offset of space heating Ipad (if known 



see text for discussion) 



SOOZ 



D-6 



APPENDIX E 
MONTHLY SOLAR ENERGY DISTRIBUTIONS 



The data tables provided in this appendix present an indication of solar 

energy distribution, intentional and unintentional, in the Montecito Pines 

solar energy system. Tables are provided for 6 months of the reporting 
period. 



E-l 



TABLE E-l. SOLAR ENERGY DISTRIBUTION - NOVEMBER 1978 

MONTECITO PINES 

10.04 million Btu TnTB1 
100% T0TAL S °LAR ENERGY COLLECTED 

4.95 million Btu rm .„ 
4g % SOLAR ENERGY TO LOADS 

1.65 million Btu r , u nn n 
1 6 - SOLAR ENERGY TO DHW SUBSYSTEM 

3.30 mil 1 ion Btu 
"33% ' SOLAR ENERGY TO SPACE HEATING SUBSYSTEM 

N.A. mil 1 ion Btu 

' SOLAR ENERGY TO SPACE COOLING SUBSYSTEM 

5.1 2 million Btu rni B „ ,. 
5f% S0LAR ENERGY LOSSES 

1 .23 mil lion Btu 
W% SOLAR ENERGY LOSS FROM STORAGE 

3.89 million Btu co , nn „. 
39 % SOLAR ENERGY LOSS IN TRANSPORT 

1 .70 million Btu 

~]Jf ' COLLECTOR TO STORAGE LOSS 

N.A. mil lion Btu„ rt 
% LU COLLECTOR TO LOAD LOSS 

N.A . mil 1 ion Btu ~ 
1 DtU COLLECTOR TO DHW LOSS 

N.A. million Btu™ 

f COLLECTOR TO SPACE HEATING LOSS 

N.A. mil 1 ion Btu 

f COLLECTOR TO SPACE COOLING LOSS 

_2^ million Btu STORAGETOL()ADLOss 

^___ million Btu ST0RAGET0DHWL()ss 

2.19 mil 1 ion Btu 
22 % STORAGE TO SPACE HfATING LOSS 

^\ milll ' 0n BtU STORAGE TO SPACE CCOLING LOSS 

-0.03 million Btu™. . 

0~% SOLAR ENERGY STORAGE CHANGE 

N.A. - Denotes not applicable data 

E-2 



TABLE E-2 S LAR ENERGY DISTRIBUTION- DECEMBER 1978 

MONTECITO PINES 

9J8 million Btu T0TA| _ S0| _ AR ENERGY CO lleCTED 
_5^08_ million Btu SOLAR £NERGY TQ L0AD$ 

2 58 million Btu SQLAR ENERGY T0 DHW SUBSYSTEM 

do lo 

^million Btu S0[ _ AR ENERGY T0 space HEATING SUBSYSTEM 



2. 

26% 



N.A. million Btu SQLAR ENERGY T0 SPACE COOLING SUBSYSTEM 
_4^1 million Btu SQLAR ENERGy lQSS£S 

HO lo 

1 70 million Btu $0LAR ENERGY L0SS FR0M STORAGE 
i / ^ 

_Ji|l million Btu S0| _ AR ENERGY L0SS IN TRA NSP0RT 
1 42 million Btu COLLECTOR TQ ST0RAGE L0SS 

I D lo 

_JLA^_ million Btu C0LLECT0R TQ LQAD L0SS 

_JL^_ million Btu C0L| _ ECT0R TQ DHW LQSS 
N.A. million Btu C0LLECT0R T0 $pACE HEATING L0SS 

lo 

N.A, million Btu C0LLECT0R TQ SpACE C0 0LING LOSS 

lo 

_L^ million Btu STQRAGE LQAD L0SS 
14 lo 

_0 million Btu STQRAGE TQ QHW LQSS 

(J /o 

""hi^ milll ° n BtU ST0RAGE TO SPACE HFATING LOSS 
N ' A V milllon Btu ST0RAGE TO SPACE COOLING LOSS 



11 ion Btu SQLAR ENERGY STORAGE CHANGE 



2% 
N.A. - Denotes not applicable data 






TABLE E-3. SOLAR ENERGY DISTRIBUTION " JANUARY 1979 

MONTECITO PINES 

7-55 million Btu,„ 
100% T0TAL SOLAR ENERGY COLLECTED 

5 -33 million Btu rftl .„ 
-TOT SOLAR ENERGY TO LOADS 

3-33 million Btu™ 
44 % SOLAR ENERGY TO DHW SUBSYSTEM 

_2 1 00_ million Btu rn , .„ 

26 % SOLAR ENERGY TO SPACE HEATING SUBSYSTEM 

N.A. million Btu cni nn _. 

% SOLAR ENERGY TO SPACE COOLING SUBSYSTEM 

2.24 million Btu rni .„ 
30 % SOLAR ENERGY LOSSES 

0-96 million Btu rni nn ,. 
13% SOLAR ENERGY LOSS FROM STORAGE 

1-27 million Btu rni nn ,. 
17% SOLAR ENERGY LOSS IN TRANSPORT 

0.57 mill ion Btu rn . . rrT ^ n _ 

8% COLLECTOR TO STORAGE LOSS 

N.A. million Btu rnnr , T 

% COLLECTOR TO LOAD LOSS 

N.A. million Btiu„ 
f t ^COLLECTOR TO DHW LOSS 

N.A. million Btu rm . „„ n „„ 

% COLLECTOR TO SPACE HEATING LOSS 

N.A. million Btu™, , ,-«,.« 

% COLLECTOR TO SPACE COOLING LOSS 

0.70 million Btu r ™ nflor . 
— 9"T STORAGE TO LOAD LOSS 

__Q million Btiu T „ nft ^ 

IT" % STORAGE TO DHW LOSS 

0. 7 million Btu 

gf STORAGE TO SPACE HEATING LOSS 

N.A. million Btu rT ^ n _ 

7, STORAGE TO SPACE COOLING LOSS 

~ - 01 million Btu CA1 Ar , „ 

% S0LAR ENERGY STORAGE CHANGE 

N.A. - Denotes not applicable data 

E-4 



TABLE E-4. SOLAR ENERGY DISTRIBUTION - FEBRUARY 1979 

MONTECITO PINES 

_jj&_ million Btu TQTAL $()LAR EN£RGY C0LLECTED 
6.38 million Btu S0LAR ENERGy TQ LQADS 



74 % 

4.01 million Btu 



46 % 
2.37 million Btu 



27 % 
N.A. million Btu 



% 
2.37 million Btu 



27 % 

0.94 mi' 
11 % 

1.43 mi" ion Btu 



SOLAR ENERGY TO DHW SUBSYSTEM 
SOLAR ENERGY TO SPACE HEATING SUBSYSTEM 
SOLAR ENERGY TO SPACE COOLING SUBSYSTEM 
ENERGY LOSSES 
SOLAR ENERGY LOSS FROM STORAGE 
SOLAR ENERGY LOSS IN TRANSPORT 

COLLECTOR TO STORAGE LOSS 
COLLECTOR TO LOAD LOSS 

COLLECTOR TO DHW LOSS 
COLLECTOR TO SPACE HEATING LOSS 
COLLECTOR TO SPACE COOLING LOSS 
STORAGE TO LOAD LOSS 

STORAGE TO DHW LOSS 

STORAGE TO SPACE HEATING LOSS 



16 % 

0.68 million Btu 

8% 

N.A. million Btu 



% 

N.A. mil 

% 

N.A. mil 

% 

N.A. mil 

% 

0.75 million Btu 



9 % 

_ million Btu 
% 

0.75 million Btu, 



9% 
JO^ million Btu STQRAGE TQ $pACE C00LING L0SS 



-O.n million Btu SQLAR ENERGY ST0RAGE CHANGE 

N.A. - Denotes not applicable data 

E-5 



TABLE E-5. SOLAR ENERGY DISTRIBUTION - MARCH 1979 

MONTECITO PINES 

9.95 million Btu T0TAL SQLAR ENERGY C0LLECTED 



100% 

7.86 mi' ion Btu 



79 % 



SOLAR ENERGY TO LOADS 



ill ion Btu $0LAR ENERGY T0 D hw SUBSYSTEM 



~4TJ 

3.14 million Btu, 



-J2-Z 'SOLAR ENERGY TO SPACE HEATING SURSYSTEM 

N.A. million Btu 



% 
1 .90 million Btu 



19 % 

0.31 mi' 

3 % 



SOLAR ENERGY TO SPACE COOLING SUBSYSTEM 
SOLAR ENERGY LOSSES 

SOLAR ENERGY LOSS FROM STORAGE 



XJj£^ million Btu SQLAR ENERGy L0SS IN TRANSPORT 
I b lo 

lion Btu C0LLECTQR TQ ST0RAGE L osS 



12 % 
N.A. million Btu 



°/ 

10 



COLLECTOR TO LOAD LOSS 



JLA^ million Btu COLLECTOR TQ DHW LQSS 

lllion Btu C0LLECT0R TQ SRACE HEATING L o SS 



% 
KJ^_ million Btu C0L| _ ECT0R TQ $pACE c0 OLING LOSS 



JL4Z_ million Btu STQRAGE T0 LQAD LQSS 

4 lo 



0^ million Btu STQRAGE TQ mw L0SS 



°lo 
42 million Btu $T0RAGE T0 $pACE HEATING L QSS 



4% 
N.A. million Btu 



% 
0.19 million Btu 



STORAGE TO SPACE COOLING LOSS 



SOLAR ENERGY STORAGE CHANGE 



2 % 
N.A. - Denotes not applicable data 

E-6 

••> U S GOVERNMENT PRINTING OFFICE 1<< *0--"lO- 1 '<>/U23t>